horizon/docs

Horizon documentation

To play, use the launcher; the project site is playhorizon.dev. These pages are for developers. What is being done now and next, the work board and how to help: the hub (ROADMAP.md, roadmap/README.md for keeping it current).

Build and run

• AGENTS.md and Architecture: where each part of the code lives, how Game is organised, which harness checks which area.
• Build from source: your own copy of the game, resource preparation, cargo run.
• Build times: tools/build_times.py measures cold and incremental builds per crate and the critical path, writes a JSON report and a table, and compares two reports; the first numbers, Windows and Linux.
• Native client: options, controls, the dedicated server, horizon-ctl scripting, packaging, architecture.
• Host a server: install horizon-server, prepare the game files, first run, server.toml, the commands, the web panel, backups, services and Docker; what works today and what doesn't yet.
• The anticheat: the dedicated server's own checks, off unless server.toml's [anticheat] turns them on: violation levels, setback, alerts, kicks, the log, and how to write a check.
• The chat filter: the dedicated server refuses hate slurs in chat, message commands, signs, anvil names and book titles: the list and its normalising, mutes, temporary bans, [chat_filter].
• Hosting a server: design: horizon-server, the design and the plan: install, server.toml, the CLI, the web panel, backups, services, Docker, and the bot benchmark against vanilla.
• The next server: design: Horizon's dedicated server against vanilla and Pumpkin (measured), the targets, parallel ticking that keeps vanilla's order, the network front, the Horizon fast path, the plugin API and the plan.
• Survival multiplayer: the official server's smp native mod (economy, market, trades, games of chance, spawn, homes, teleport requests, warps, land claims) and the server hook points it needs; not part of Horizon's own server.
• For server owners: every server.properties key next to its server.toml field.
• Agent control: what AI agents can drive in the launcher and the game, and the design of the control socket, horizon-ctl and MCP.
• Graphics: the Simple and Advanced graphics settings, the graphics benchmark and what it measured.
• Server against Pumpkin: Horizon's server and Pumpkin (Rust) under the same bots at 0, 20, 60 and 100 players: tick time, CPU, memory, chunks, join; where Horizon loses, and how to run it again.
• Benchmark: Horizon against vanilla 26.3 and vanilla with performance mods, on the same machine, world, path and settings: what is measured, how it is kept fair, how to reproduce it.
• Extras: optional zoom, minimap, FPS and keystroke overlays and auto-reconnect, all off by default.
• Narrator: vanilla's text-to-speech (Ctrl+B): the voices per platform, how screens record what they narrate, horizon-ctl narration, and where it still differs from vanilla.
• Shader packs: Horizon's own WGSL shader packs, how to make and check one (horizon-shader).
• Mods: content mods (data) and native mods (Rust), how to make, install and publish them. Native mods: how the launcher builds them. Native hook points modelled on NeoForge: the proposal for new hooks.
• Upgrading a 26.2 data pack: horizon-port-pack upgrade-datapack rewrites a 26.2 worldgen pack in 26.3's formats, and how the rewrite is checked against vanilla.
• Modpacks: porting whole packs (ATM10 and smaller): import, inventory, carry-over, an agent per mod with a harness against the Java original, coverage, and how "10x" is measured.
• Launcher: installs, updates and starts builds; its CLI and MCP server; releasing it.
• Versioning: how releases are numbered from 0.2 (v0.2.x, [email protected]), how installs from before 0.2 get there, and the steps for the day 0.2 ships.
• Resource packs: everything a 26.3 resource pack can change, whether Horizon honours it, and the proof.
• Opt-in data collection: the consent, exactly what is sent, how it is stored and sent.
• Benchmark report format: the versioned JSON every benchmark writes (game, launcher, tools/perf_bench.py), the local log and, with consent, the upload.
• Horizon APIs: every surface other programs build on (mods, shaders, agent control, servers, the launcher, data formats), each with its guide, generated reference, stability and changelog, and the stability and versioning policy.
• Menus: every screen is vanilla's (title, world list, create world, multiplayer, options, pause). Horizon's own settings hang off vanilla's Options the way mods add theirs: Horizon Settings... and Mods... in the last two slots of the Options grid (Horizon Settings opens Graphics, Advanced Graphics, Controller Settings, Extras and Mods, each a vanilla options list), with Horizon Graphics and Advanced Graphics also at the top of Video Settings and Controller Settings at the bottom of Controls. The title screen's and pause menu's Friends buttons open Join a Friend and Play with Friends (play-with-friends.md).

Parity

• Rust rewrite status: completion criteria, how to reproduce the validation, and per-area scope.
• Parity workflow: tools/parity.py, the gate, other machines, merging.
• CI runners: which jobs run on GitHub's runners and which on ours (playhorizon, the Mac mini), and why a fork's pull request never runs on ours.
• Area notes: block behaviours and ticking, section meshing.
• Port ledger: tools/port_ledger.py, every vanilla method next to the Rust functions that port it, both ways, with the gaps where a port isn't wired like vanilla.
• Version ports: how a new Minecraft release is detected, diffed against the pinned one and ported, and what stays manual.
• Decompilation and research lab and decompilation status: the local game inspection workspace the harnesses build on.

Architecture: world generation

• World generation: the pipeline from noise to features.
• World height: each level's shape from its dimension type, data packs' taller levels.
• Pregeneration: /pregen, generating, lighting and saving an area ahead of the players.
• Noise generation, compiled density functions, structure density, terrain filling.
• Biomes: lookup, temperatures.
• Surfaces: material surfaces, material conditions, rule libraries, vertical anchors, value providers.
• Carving, heightmaps, feature placement.

Architecture: world data and simulation

• World data: chunk storage, palettes, region files.
• Block-state codecs, scheduled ticks.
• Collision geometry: shapes, collision, movement and fluids.
• Face visibility: which model faces the mesher emits.

Java comparison profiling

• JFR analysis for Java comparisons.